The girl was reportedly having seizures and emergency responders measured her fever at 105.7 degrees. According to CBP, the girl had "not eaten or consumed water for several days."

The unnamed child was airlifted to a hospital in El Paso, where CBP said she later died.

Border security has been a central pillar in Trump's tough immigration agenda, most recently the president offered to shut down the government while sparring with leading Democrats over his headline border wall project.

A 7-year-old girl from Guatemala died at an El Paso hospital just eight hours after Border Patrol took her into custody, The Washington Post reported on Thursday.

The girl and her father were part of a group of 163 migrants who turned themselves in to officials in New Mexico, US Customs and Border Protection told The Post.

The group was taken into custody in the New Mexico desert six miles south of Lordsburg, N.M. at 9:15 p.m. local time on December 6, according to a timeline from CBP. A little more than 8 hours later, at 6:25 a.m. local time, the girl was reportedly having seizures and emergency responders measured her fever at 105.7 degrees.

CBP told The Post, the girl "reportedly had not eaten or consumed water for several days."

After being airlifted to a hospital in El Paso, she went into cardiac arrest, was revived, but did not survive the ordeal.

"[T]he child did not recover and died at the hospital less than 24 hours after being transported," CBP said. Autopsy results will not be available for several weeks, however, "El Paso's Providence Hospital listed the cause of death as septic shock, fever and dehydration," The Post reported. CBP said in a statement that they will investigate to make sure policies were followed.

According to the CPB timeline, officials were made aware that she was ill and vomiting at around 5:00 a.m. on the bus ride to the Lordsburg Border Patrol Station. Prior to being bused to Lordsburg, the migrants were at the Sally Port of the Antelope Wells Port of Entry and reportedly "had access to food, water and restrooms," CBP said.

An email to INSIDER from the Department of Homeland Security explained that DHS has warned that traveling north to a border crossing is "extremely dangerous" and poses a significant risk.

"Unfortunately, despite our best efforts and the best efforts of the medical team treating the child, we were unable to stop this tragedy from occurring," the department said. "Once again, we are begging parents to not put themselves or their children at risk attempting to enter illegally."

"On behalf of the Department of Homeland Security, our sincerest condolences go out to the family of the child," the statement added. "Border Patrol agents took every possible step to save the child's life under the most trying of circumstances."

The girl's death is likely to heighten scrutiny of Border Patrol and CBP, two agencies already under the microscope following a succession of controversial White House policies targeting the US southern border and immigrant detention.

While the greater attention has centered on the "caravan" of Central American migrants now in Tijuana, Mexico, due to heightened politicization of the migrants prior to the midterm elections, there have also been smaller groups making their way across the desert in Texas, Arizona, and New Mexico.

The Post says the number of family units coming across has increased, and the CBP admits it's is not adequately equipped.

Earlier this year the White House invoked a "zero tolerance" approach to these kinds of crossings, initially separating parents and children at the border, then changing sudden course in June, ahead of a court judgement reuniting separated families.

NPR reports there are still roughly 15,000 children in Department of Health and Human Services custody, largely unaccompanied minors that made the crossing alone and now due to a more stringent vetting process for potential sponsors, are waiting to be transferred to parents or guardians who are already in the US.

Many Central American migrants hope to secure asylum in the US far from violent homelands, while the Trump administration is determined to block anyone who does not enter the US at an official port of entry port of entry from being eligible for asylum. This week the Trump administration asked the US Supreme Court to weigh in after it was blocked in lower courts.

All this has made the actions of border security a potential lightning rod within Trump's political agenda. Earlier this week the president publicly sparred with House Minority Leader Nancy Pelosi and Senate Minority Leader Chuck Schumer over his proposed border wall, eagerly assuming responsibility for any government shutdown stemming form challenges over its funding.

Updated 12/14/2018 at 3:46 p.m. PT: This piece was updated with new information from CBP.